public class Practice {
    //山脉数组的峰顶索引
    class Solution {
        public int peakIndexInMountainArray(int[] arr) {
            int left=0,right=arr.length-1;
            while(left<right){
                int mid=left+(right-left)/2;
                if(arr[mid]>arr[mid+1]){
                    right=mid;
                }else{
                    left=mid+1;
                }
            }
            return left;
        }
    }

}
